Heretofore, drivers have received traffic congestion information announced over radio and television stations. Information communicated in such fashion has several disadvantages: it is generally delayed from the time of observation of the traffic conditions; it is announced from time-to-time and not necessarily at the time needed by a driver; and, it is generally addressed to a broader audience than individual drivers and their intended courses of travel. Also, traffic congestion information has been communicated over telephones (including mobile and cellular telephones). The primary disadvantage here is that the availability of information is limited to times when the driver can use a telephone. Also, traffic congestion information services have communicated information using radio pagers with alphanumeric display capability. The primary disadvantages of this approach is that the amount of information capable of being viewed is limited, and viewing visual information in a moving vehicle can be a safety hazard.
Experimental projects in Los Angeles, Calif., and Orlando, Fla., have provided traffic congestion information to receiving units mounted in vehicles. These units include a visual screen showing the position of the vehicle on a map. Information is presented both visually and via synthesized speech. The primary disadvantage of this approach is that information about congestion is frequently of interest outside the car, for example, in deciding whether to take a trip, or when to depart. Furthermore, these systems are hardware intensive and therefore are relatively expensive.
U.S. Pat. No. 4,480,253 (entitled: "Wrist Watch Weather Radio") describes the distribution of weather information to portable units over radio frequencies. However, this patent does not cover the distribution of traffic congestion information or methods for selecting specific locations of interest.
U.S. Pat. No. 4,812,843 (entitled: "Telephone Accessible Information System") describes the communication of route-specific traffic congestion information. The disadvantage of this approach is that route selections require telephone access to a central computer data base and thus cannot be conveniently used for instant response regarding trips not pre-selected by telephone.